Radio communication apparatus, radio communication system and radio communication method

ABSTRACT

A radio communication apparatus selectively performs one of a first transmission method using for data transmission a radio resource which is assigned by a radio communication apparatus and which can be used on a contention basis by a plurality of radio communication apparatus and a second transmission method involving random access. Alternatively, the radio communication apparatus selectively performs one of the first transmission method and a third transmission method involving a request made to the radio communication apparatus to assign a radio resource for data transmission.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of InternationalApplication PCT/JP2010/052102 filed on Feb. 12, 2010 and designated theU.S., the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to a radio communicationapparatus, a radio communication system, and a radio communicationmethod.

BACKGROUND

At present many radio communication systems, such as portable telephonesystems and radio MANs (Metropolitan Area Networks), are used. Inaddition, in order to further increase the speed and capacity of radiocommunication, lively discussions on next generation radio communicationtechniques are being conducted continuously.

For example, 3GPP (3rd Generation Partnership Project) which is astandardization organization proposed a communication standard which isreferred to as LTE (Long Term Evolution) and by which communication canbe performed by the use of a maximum of 20-megahertz frequency band.Furthermore, 3GPP proposed as a next generation communication standardfor LTE a communication standard which is referred to as LTE-A(LTE-Advanced) and by which communication can be performed by the use ofa maximum of 100-megahertz frequency band (see, for example, NPTL1).

In many radio communication systems a procedure under which one radiocommunication apparatus (mobile station, for example) transmits data tothe other radio communication apparatus (base station, for example) froma state in which a radio resource used for data transmission is notassigned thereto is stipulated. Examples of such a procedure are (1)method by which random access is performed (see, for example, Paragraph10.1.5 of NPTL2 or Paragraph 5.1 of NPTL3) and (2) method by which ascheduling request is transmitted (see, for example, Paragraph 5.2.3 ofNPTL2 or Paragraph 5.4.4 of NPTL3).

When a mobile station performs random access to a base station, themobile station transmits a signature which it selects at random fromamong a plurality of signatures to the base station as a random accesspreamble. The base station transmits a random access response as aresponse. After that, the mobile station transmits its identifier to thebase station and the base station notifies the mobile station that itcan recognize the mobile station. As a result, mobile stations go into astate in which they can be assigned radio resources individually by thebase station for data transmission. With this method, however, randomaccess contention may occur among a plurality of mobile stations. Thisleads to failure in a procedure.

With the method by which a mobile station transmits a scheduling requestto a base station, the base station assigns in advance to the mobilestation a control channel radio resource for transmitting the schedulingrequest. The mobile station uses the control channel radio resource fortransmitting the scheduling request to the base station. The basestation assigns radio resources for data transmission to mobile stationsindividually and notifies the mobile stations of the radio resourceassigned thereto. As a result, each mobile station goes into a state inwhich it can perform data transmission.

With LTE-A, on the other hand, a reduction in delay time from a dormantstate in which data transmission is not performed temporarily because ofthe intermittence of packet communication to the resumption of datatransmission is under examination (see, for example, Paragraph 10.1 ofNPTL4). (3) contention based uplink access is proposed as a method forrealizing this (see, for example, NPTL5).

With the contention based uplink access from a mobile station to a basestation, for example, the base station sets a radio resource (contentionbased radio resource) which a plurality of mobile stations can share fordata transmission, that is to say, a radio resource which is notassigned individually to a plurality of mobile stations. When a mobilestation detects the contention based radio resource, the mobile stationuses the radio resource for data transmission without receivingparticular permission from the base station. This reduces time whichelapses before the beginning of data transmission by the mobile station.However, data transmission contention may occur among a plurality ofmobile stations. This leads to failure in a procedure.

-   NPTL1: 3GPP (3rd Generation Partnership Project), “Requirements for    Further Advancements for Evolved Universal Terrestrial Radio Access    (E-UTRA) (LTE-Advanced)”, 3GPP TR 36.913, V8.0.1, 2009-03.-   NPTL2: 3GPP (3rd Generation Partnership Project), “Evolved Universal    Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial    Radio Access Network (E-UTRAN); Overall description”, 3GPP TS    36.300, V9.0.0, 2009-06.-   NPTL3: 3GPP (3rd Generation Partnership Project), “Evolved Universal    Terrestrial Radio Access (E-UTRA) Medium Access Control (MAC)    protocol specification”, 3GPP TS 36.321, V9.1.0, 2009-12.-   NPTL4: 3GPP (3rd Generation Partnership Project), “Feasibility study    for Further Advancements for E-UTRA (LTE-Advanced)”, 3GPP TR 36.912,    V9.0.0, 2009-09.-   NPTL5: 3GPP (3rd Generation Partnership Project), “Contention based    uplink transmissions”, 3GPP TSG-RAN WG2 #66bis R2-093812, 2009-06.

As stated above, there are a plurality of methods for beginning datatransmission from a state in which a radio resource used for datatransmission is not assigned individually. However, how to use theseaccess methods is problematic. In particular, if a contention basedradio resource is set as proposed in the above NPTL5, the relationshipbetween the method using the contention based radio resource and theother access methods is problematic.

SUMMARY

According to an aspect of the embodiments, there is provided a radiocommunication apparatus used as one of a plurality of second radiocommunication apparatus in a radio communication system in which a firstradio communication apparatus receives data from the plurality of secondradio communication apparatus, the radio communication apparatusincluding: a detection section which detects a first radio resource thatis assigned by the first radio communication apparatus and that can beused on a contention basis by the plurality of second radiocommunication apparatus for data transmission; and a transmissionprocessing section which selectively performs, at the time of the firstradio resource being detected, one of a first transmission method usingthe first radio resource for data transmission and a second transmissionmethod using a second radio resource assigned by the first radiocommunication apparatus by which random access is performed for datatransmission.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 illustrates a radio communication system according to a firstembodiment;

FIG. 2 illustrates a mobile communication system according to a secondembodiment;

FIG. 3 is a sequence diagram of a random access procedure;

FIG. 4 is a sequence diagram of a scheduling request procedure;

FIG. 5 is a sequence diagram of a contention based uplink accessprocedure;

FIG. 6 is a block diagram of a base station;

FIG. 7 is a block diagram of a mobile station;

FIG. 8 is a flow chart of a process performed by a base station in thesecond embodiment;

FIG. 9 is a flow chart of a process performed by a mobile station in thesecond embodiment;

FIG. 10 is a first example of a sequence in the second embodiment;

FIG. 11 is a second example of a sequence in the second embodiment;

FIG. 12 is a third example of a sequence in the second embodiment;

FIG. 13 is a fourth example of a sequence in the second embodiment;

FIG. 14 is a flow chart of a process performed by a base station in athird embodiment;

FIG. 15 is a flow chart of a process performed by a mobile station inthe third embodiment;

FIG. 16 is a first example of a sequence in the third embodiment;

FIG. 17 is a second example of a sequence in the third embodiment;

FIG. 18 is a flow chart of a process performed by a mobile station in afourth embodiment;

FIG. 19 is a first example of a sequence in the fourth embodiment;

FIG. 20 is a second example of a sequence in the fourth embodiment;

FIG. 21 is a flow chart of a process performed by a mobile station in afifth embodiment;

FIG. 22 is a first example of a sequence in the fifth embodiment;

FIG. 23 is a second example of a sequence in the fifth embodiment;

FIG. 24 is a third example of a sequence in the fifth embodiment;

FIG. 25 is a flow chart of a process performed by a base station in asixth embodiment;

FIG. 26 is a flow chart of a process performed by a mobile station inthe sixth embodiment;

FIG. 27 is a first example of a sequence in the sixth embodiment;

FIG. 28 is a second example of a sequence in the sixth embodiment;

FIG. 29 is a flow chart of a process performed by a mobile station in aseventh embodiment;

FIG. 30 is a first example of a sequence in the seventh embodiment;

FIG. 31 is a second example of a sequence in the seventh embodiment;

FIG. 32 is a first example of a sequence in an eighth embodiment; and

FIG. 33 is a second example of a sequence in the eighth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments will now be described in detail with reference to thedrawings.

First Embodiment

FIG. 1 illustrates a radio communication system according to a firstembodiment. A radio communication system according to a first embodimentincludes radio communication apparatus 1 through 3. Such a radiocommunication system can be realized as, for example, an LTE-A system.

The radio communication apparatus 1 controls radio resource assignment.The radio communication apparatus 2 and 3 transmit data to the radiocommunication apparatus 1 under the control of the radio communicationapparatus 1. For example, the radio communication apparatus 1 can berealized as a base station or a relay station and the radiocommunication apparatus 2 and 3 can be realized as subscriber stations.The radio communication apparatus 1 through 3 may be fixed radiocommunication apparatus or mobile radio communication apparatus. In thefirst embodiment it is assumed that the radio communication apparatus 2and 3 begin data transmission from a state (dormant state, for example)in which radio resources used for data transmission are not assignedindividually.

The radio communication apparatus 1 includes a control section 1 a and anotification section 1 b. The control section 1 a configures a radioresource which the radio communication apparatus 2 and 3 can use on acontention basis for data transmission, that is to say, a contentionbased radio resource. A contention based radio resource may be set in,for example, a constant period. In addition, the control section 1 a canassign to the radio communication apparatus 2 and 3 a control channelradio resource used for transmitting a radio resource assignmentrequest. The notification section 1 b notifies the radio communicationapparatus 2 and 3 of at least one of information indicating thecontention based radio resource and information indicating the controlchannel radio resource.

The radio communication apparatus 2 includes a detection section 2 a anda transmission processing section 2 b. The detection section 2 a detectsat least one of the contention based radio resource configured by theradio communication apparatus 1 and the control channel radio resourceassigned by the radio communication apparatus 1. For example, on thebasis of the information of which the radio communication apparatus 1notifies the radio communication apparatus 2, the detection section 2 adetects these radio resources. The transmission processing section 2 btransmits data to the radio communication apparatus 1 according to thestate of detection by the detection section 2 a. The radio communicationapparatus 3 can also be realized by the same structure that is adoptedin the radio communication apparatus 2.

Data transmission methods performed by the transmission processingsection 2 b include a method for performing random access and receivingradio resource assignment (transmission method 1), a method fortransmitting an assignment request using a control channel radioresource and receiving radio resource assignment (transmission method2), and a method for transmitting data using a contention based radioresource (transmission method 3). The transmission processing section 2b does not perform these three transmission methods in parallel butselectively performs one of them.

For example, if a contention based radio resource is detected, then thetransmission processing section 2 b selectively performs one of thetransmission method 1 and the transmission method 3 (that is to say, thetransmission processing section 2 b does not perform the transmissionmethod 1 and the transmission method 3 in parallel). First thetransmission processing section 2 b performs only one of them. If aprocedure for the transmission method fails, then the transmissionprocessing section 2 b may abort the procedure which is being performed,and perform the other transmission method. Which to perform first may bedetermined in advance. Furthermore, if a control channel radio resourceis detected, then the transmission processing section 2 b selectivelyperforms one of the transmission method 1 and the transmission method 3.

In addition, if both of a contention based radio resource and a controlchannel radio resource assigned to the radio communication apparatus 2by the radio communication apparatus 1, for example, are detected, thenthe transmission processing section 2 b selectively performs one of thetransmission method 2 and the transmission method 3. First thetransmission processing section 2 b performs only one of them. If aprocedure for the transmission method fails, then the transmissionprocessing section 2 b may abort the procedure which is being performed,and perform the other transmission method. Which to perform first may bedetermined in advance or be determined according to the type of data tobe transmitted. Alternatively, the transmission processing section 2 bmay selectively perform one of the transmission method 1, thetransmission method 2, and the transmission method 3.

In addition, the radio communication apparatus 1 can execute control sothat the radio communication apparatus 2 can perform only one of thetransmission method 2 and the transmission method 3. For example, if theradio communication apparatus 1 makes the radio communication apparatus2 perform the transmission method 2, then the radio communicationapparatus 1 notifies the radio communication apparatus 2 of a controlchannel radio resource assigned thereto and does not notify the radiocommunication apparatus 2 of permission to use a contention based radioresource. On the other hand, if the radio communication apparatus 1makes the radio communication apparatus 2 perform the transmissionmethod 3, then the radio communication apparatus 1 notifies the radiocommunication apparatus 2 of permission to use a contention based radioresource, and does not assign a control channel radio resource to theradio communication apparatus 2. If the radio communication apparatus 1makes the radio communication apparatus 2 determine one of thetransmission method 2 and the transmission method 3 to be performed,then the radio communication apparatus 1 notifies the radiocommunication apparatus 2 of both of a control channel radio resourceassigned thereto and permission to use a contention based radioresource.

According to the radio communication system according to the above firstembodiment a procedure for data transmission performed in the case of acontention based radio resource being configured can be made efficient.That is to say, it is possible to prevent the radio communicationapparatus 2 from performing the above transmission method 1 andtransmission method 3 in parallel or from performing the abovetransmission method 2 and transmission method 3 in parallel. This makesit easy to control data transmission from the radio communicationapparatus 2 and 3 to the radio communication apparatus 1. In addition,it is possible to avoid assigning a plurality of radio resources forperforming data transmission once. As a result, efficiency in the use ofa radio resource can be improved.

In the following second through seventh embodiments a case where theradio communication method in the first embodiment is applied to anLTE-A mobile communication system will be described in further detail.However, the radio communication method in the first embodiment can alsobe applied to a mobile communication system using a communication schemeother than LTE-A or a fixed radio communication system.

Second Embodiment

FIG. 2 illustrates a mobile communication system according to a secondembodiment. A mobile communication system according to a secondembodiment includes a base station 10, mobile stations 20 and 20 a, anda relay station 30.

The base station 10 is a radio communication apparatus which performscommunication directly or via the relay station 30 with the mobilestations 20 and 20 a. The base station 10 is connected to an upperstation (not illustrated) by wire and transfers user data between awired interval and a radio interval. The base station 10 manages a radioresource for links with the mobile stations 20 and 20 a and a radioresource for a link with the relay station 30.

Each of the mobile stations 20 and 20 a is a radio terminal device whichgains access to the base station 10 or the relay station 30 forperforming radio communication. Portable telephones, personal digitalassistants, or the like can be used as the mobile stations 20 and 20 a.For example, the mobile stations 20 and 20 a are in a dormant state inwhich they do not perform data communication or in an active state inwhich they can perform data communication. When the mobile station 20 or20 a returns from a dormant state to an active state, it performs one ofa random access procedure, a scheduling request procedure, and acontention based uplink access procedure described later.

The relay station 30 is a radio communication apparatus which relaysdata transmission between the base station 10 and the mobile stations 20and 20 a. The relay station may be a fixed communication apparatus or amobile communication apparatus. The relay station 30 manages a radioresource for links with the mobile stations 20 and 20 a.

In the following description it is assumed that the mobile station 20transmits data to the base station 10. The same applies to a case wherethe mobile station 20 transmits data to the relay station 30 or a casewhere the mobile station 20 a transmits data to the base station 10 orthe relay station 30.

FIG. 3 is a sequence diagram of a random access procedure.

(Step S11) The mobile station 20 selects one of a plurality ofsignatures defined in advance. The mobile station then transmits arandom access preamble using the selected signature to the base station10 on PRACH (Physical Random Access Channel). At this time a pluralityof mobile stations may transmit the same signature at the same timing onthe PRACH. That is to say, random access contention may occur.

(Step S12) When the base station 10 detects the random access preamble,the base station 10 transmits a random access response. If contentionoccurs, then each mobile station which transmits a random accesspreamble receives a random access response.

(Step S13) When the mobile station 20 receives the random accessresponse, the mobile station 20 transmits to the base station 10 ascheduled transmission including a C-RNTI (Cell Radio Network TemporaryIdentifier) of the mobile station 20. If contention occurs, then aplurality of mobile stations transmit scheduled transmissions using thesame radio resource. In this case, these messages interfere with oneanother.

(Step S14) The base station 10 receives the scheduled transmission andrecognizes from the C-RNTI the mobile station 20 which transmits thescheduled transmission. The base station 10 then transmits to the mobilestation 20 a contention resolution which indicates that the base station10 succeeds in recognizing the mobile station 20. After that,synchronization is established between the base station 10 and themobile station 20 and data communication can be performed.

If contention occurs, then the base station 10 cannot normally detect aC-RNTI included in a scheduled transmission. In this case, the randomaccess procedure fails. After the mobile station 20 waits for randomtime, the mobile station 20 returns to step S11 and performs the randomaccess procedure again.

However, the random access procedure may fail repeatedly. In this case,after the mobile station 20 performs the random access procedure acertain number of times or after a certain period of time elapses, themobile station 20 terminates the random access procedure. Morespecifically, at least one of a maximum number of times random access isperformed and maximum time is set for the mobile station 20. When thenumber of times random access is performed reaches the maximum number oftimes or when the maximum time elapses after the first transmission of arandom access preamble, the mobile station 20 terminates the randomaccess procedure.

FIG. 4 is a sequence diagram of a scheduling request procedure.

(Step S21) The base station 10 assigns to the mobile station 20 a PUCCH(Physical Uplink control channel) radio resource for transmitting ascheduling request. A PUCCH radio resource is configured in a constantperiod. The base station 10 then transmits to the mobile station 20information indicating the radio resource assigned thereto. For example,the base station 10 notifies the mobile station 20 of timing of asubframe and a position in the subframe.

(Step S22) The mobile station 20 uses the radio resource of which it isnotified by the base station 10 for transmitting a scheduling request tothe base station 10. Scheduling request contention does not occur.However, there is a possibility that the scheduling request procedurefails. The reason for this is that the base station 10 cannot normallyreceive the scheduling request.

(Step S23) The base station 10 assigns to the mobile station 20 a PUSCH(Physical Uplink Shared Channel) radio resource used for transmitting ULdata. The base station 10 then transmits to the mobile station 20 a ULgrant indicating the radio resource assigned thereto. If there is a lackof radio resources to be assigned to the mobile station 20, then thescheduling request procedure may fail at this point of time.

(Step S24) The mobile station 20 uses the PUSCH radio resource of whichit is notified by the base station 10 for transmitting data to the basestation 10. On the other hand, if the scheduling request procedure failsand the mobile station 20 cannot receive a UL grant, then the mobilestation 20 uses the radio resource which is configured in the constantperiod and of which it is notified in step S21 for retransmitting ascheduling request.

However, the scheduling request procedure may fail repeatedly. In thiscase, after the mobile station 20 makes a scheduling request a certainnumber of times or after a certain period of time elapses, the mobilestation 20 terminates the scheduling request procedure. Morespecifically, at least one of a maximum number of times a schedulingrequest is made and maximum time is configured for the mobile station20. When the number of times a scheduling request is transmitted reachesthe maximum number of times or when the maximum time elapses after thefirst transmission of a scheduling request, the mobile station 20terminates the scheduling request procedure.

FIG. 5 is a sequence diagram of a contention based uplink accessprocedure.

(Step S31) The base station 10 gives the mobile station 20 a CB-RNTIwhich is an identifier different from a C-RNTI. The base station 10 thennotifies the mobile station 20 of the CB-RNTI. Giving the CB-RNTI meansgranting permission to perform contention based uplink access. The basestation 10 can give a plurality of mobile stations the same CB-RNTI. Byincreasing or decreasing the number of mobile stations to which the sameCB-RNTI is given, the probability of the occurrence of contention can becontrolled.

(Step S32) The base station 10 configures a contention based radioresource (CB resource). The base station 10 then transmits to the mobilestation 20 a CB grant indicating the configured CB resource. There arevarious CB resource assignment methods including, for example, a methodby which a CB resource is configured in a constant period and a methodby which a single CB resource is assigned by a UL grant. In addition,there are various CB grant assignment methods including, for example, amethod by which a CB grant is transmitted from the base station 10 tothe mobile station 20 in a constant period and a method by which, like aUL grant, a single CB grant is assigned.

(Step S33) The base station 10 transmits the CB grant to the mobilestation 20. It is assumed that at this point of time UL transmitted datahas been generated in the mobile station 20.

(Step S34) The mobile station 20 uses the CB resource of which it isnotified in step S33 by the base station 10 for transmitting the data tothe base station 10. However, contention may occur among a plurality ofmobile stations. That is to say, a plurality of mobile stations may usethe same CB resource for transmitting data. In this case, the mobilestation 20 retransmits the data using a subsequent CB resource.

However, data transmission using a CB resource may fail repeatedly. Inthis case, after the mobile station 20 performs data transmission by aCB resource a certain number of times or after a certain period of timeelapses, the mobile station 20 terminates the contention based uplinkaccess procedure. More specifically, at least one of a maximum number oftimes contention based uplink access is performed and maximum time isconfigured for the mobile station 20. When the number of times datatransmission is performed reaches the maximum number of times or whenthe maximum time elapses after the first data transmission by a CBresource, the mobile station 20 terminates the contention based uplinkaccess procedure.

FIG. 6 is a block diagram of the base station. The base station 10includes a radio communication section 11, a scheduler 12, a wiredcommunication section 13, a control section 14, a control plane unit 15,a resource assignor 16, a data plane unit 17, and a resource determiner18.

The radio communication section 11 is a radio interface which performsradio communication with the mobile stations 20 and 20 a and the relaystation 30. The radio communication section 11 performs signalprocessing including demodulation and decoding on a radio signalreceived from the mobile station 20 or 20 a or the relay station 30, andextracts user data and control information. In addition, the radiocommunication section 11 performs signal processing including coding andmodulation on user data and control information to be transmitted to themobile station 20 or 20 a or the relay station 30, and radio-transmitsthem.

In accordance with instructions from the control section 14, thescheduler 12 assigns radio resources to the mobile stations 20 and 20 aand the relay station 30 (scheduling). For example, the scheduler 12assigns a PUCCH or PUSCH radio resource to the mobile station 20 or 20 aand sets a CB resource.

The wired communication section 13 is a communication interface whichperforms wired communication with the upper station. The wiredcommunication section 13 receives from the upper station user data adestination of which is the mobile station 20 or 20 a. The received userdata is transferred to the mobile station 20 or 20 a under scheduling bythe scheduler 12. In addition, the wired communication section 13transfers user data extracted by the radio communication section 11 tothe upper station.

The control section 14 controls processing by the radio communicationsection 11, the scheduler 12, and the wired communication section 13.The control section 14 includes the control plane unit 15 and the dataplane unit 17. The control plane unit 15 includes the resource assignor16. The data plane unit 17 includes the resource determiner 18.

The control plane unit 15 controls transmitting control information toor receiving control information from the mobile stations 20 and 20 aand the relay station 30. That is to say, the control plane unit 15acquires control information extracted by the radio communicationsection 11, and executes communication control according to the controlinformation. In addition, the control plane unit 15 notifies the radiocommunication section 11 of control information to be transmitted to themobile station 20 or 20 a or the relay station 30. For example, thecontrol plane unit 15 processes an RRC (Radio Resource Control)protocol.

The resource assignor 16 manages radio resources used by the mobilestations 20 and 20 a for accessing the base station 10. For example, theresource assignor 16 determines whether to permit the mobile station 20or 20 a to use a CB resource or whether to assign a PUCCH radio resourceto the mobile station 20 or 20 a.

The data plane unit 17 controls transmitting user data to or receivinguser data from the mobile stations 20 and 20 a and the relay station 30.For example, the data plane unit 17 processes a PDCP (Packet DataConvergence Protocol), an RLC (Radio Link Control) protocol, and a MAC(Media Access Control) protocol.

The resource determiner 18 determines a type of a radio resource bywhich user data that is received from the mobile station 20 or 20 a andthat is extracted by the radio communication section 11 is received. Theresource determiner 18 then determines a process to be performed nextaccording to the determined type of the radio resource.

FIG. 7 is a block diagram of the mobile station. The mobile station 20includes a radio communication section 21, a transmission processingsection 22, a control section 23, a control plane unit 24, a resourcesetter 25, a data plane unit 26, and a method determiner 27.

The radio communication section 21 is a radio interface which performsradio communication with the base station 10 and the relay station 30.The radio communication section 21 performs signal processing includingdemodulation and decoding on a radio signal received from the basestation 10 or the relay station 30, and extracts user data and controlinformation. In addition, the radio communication section 21 performssignal processing including coding and modulation on user data andcontrol information to be transmitted to the base station 10 or therelay station 30, and radio-transmits them.

The transmission processing section 22 uses a UL access method and aradio resource designated by the control section 23 for transmittingdata to the base station 10 or the relay station 30. For example, thetransmission processing section 22 generates various messages includinga random access preamble and a scheduling request, and outputs them tothe radio communication section 21.

The control section 23 controls processing by the radio communicationsection 21 and the transmission processing section 22. The controlsection 23 includes the control plane unit 24 and the data plane unit26. The control plane unit 24 includes the resource setter 25. The dataplane unit 26 includes the method determiner 27.

The control plane unit 24 controls transmitting control information toor receiving control information from the base station 10 and the relaystation 30. That is to say, the control plane unit 24 acquires controlinformation extracted by the radio communication section 21, andexecutes communication control according to the control information. Inaddition, the control plane unit 24 notifies the radio communicationsection 21 of control information to be transmitted to the base station10 or the relay station 30. For example, the control plane unit 24processes an RRC protocol.

On the basis of control information received from the base station 10 orthe relay station 30, the resource setter 25 manages a UL radio resourcewhich the mobile station 20 can use. When the mobile station 20transmits data to the base station 10 or the relay station 30, theresource setter 25 notifies the transmission processing section 22 of aUL radio resource.

The data plane unit 26 controls transmitting user data to or receivinguser data from the base station 10 and the relay station 30. Forexample, the data plane unit 26 processes a PDCP, an RLC protocol, and aMAC protocol.

When the mobile station 20 returns from a dormant state to an activestate, the method determiner 27 determines which of the random accessmethod, the scheduling request method, and the contention based uplinkaccess method to use. The method determiner 27 then notifies thetransmission processing section 22 of the determined method.

The mobile station 20 a can also be realized by the same structure thatis adopted in the mobile station 20. Like the base station 10, the relaystation 30 may include a radio communication section and a controlsection. In this case, in connection with access to the relay station 30by the mobile station 20 or 20 a, the control section of the relaystation 30 performs the same process that the control section 14 of thebase station 10 performs.

FIG. 8 is a flow chart of a process performed by the base station in thesecond embodiment. The process indicated in FIG. 8 will be described inorder of step number.

(Step S111) The control section 14 selects only one of a CB resource anda PUCCH radio resource as a radio resource the use of which it permitsthe mobile station 20. For example, if a PUCCH radio resource isassigned to the mobile station 20, then the control section 14 does notpermit the mobile station 20 to use a CB resource. On the other hand, ifa PUCCH radio resource is not assigned to the mobile station 20, thenthe control section 14 permits the mobile station 20 to use a CBresource.

(Step S112) The control section 14 determines whether or not it selectsa CB resource in step S111. If the control section 14 selects a CBresource in step S111, then step S113 is performed. If the controlsection 14 selects a PUCCH radio resource in step S111, then step S114is performed.

(Step S113) The radio communication section 11 notifies the mobilestation 20 of a CB-RNTI. In addition, the radio communication section 11continuously notifies the mobile station 20 of a CB grant indicating theCB resource. Step S115 is then performed.

(Step S114) The scheduler 112 assigns a PUCCH radio resource to themobile station 20. The radio communication section 11 notifies themobile station 20 of the radio resource assigned thereto.

(Step S115) The control section 14 determines whether or not it detectsdata which the mobile station 20 transmits using the CB resource. If thecontrol section 14 detects data which the mobile station 20 transmitsusing the CB resource, then step S116 is performed. If the controlsection 14 does not detect data which the mobile station 20 transmitsusing the CB resource, then step S117 is performed.

(Step S116) The radio communication section 11 and the wiredcommunication section 13 extract the data detected in step S115, andtransfer it to the upper station. The process then terminates.

(Step S117) The control section 14 determines whether or not it detectsa scheduling request which the mobile station 20 transmits using thePUCCH radio resource assigned thereto in step S114. If the controlsection 14 detects a scheduling request which the mobile station 20transmits using the PUCCH radio resource assigned thereto in step S114,then step S118 is performed. If the control section 14 does not detect ascheduling request which the mobile station 20 transmits using the PUCCHradio resource assigned thereto in step S114, then step S119 isperformed.

(Step S118) The scheduler 12 assigns a PUSCH radio resource to themobile station 20. The radio communication section 11 notifies themobile station 20 of a UL grant indicating the radio resource assignedthereto. After that, the radio communication section 11 and the wiredcommunication section 13 extract data which the mobile station 20transmits using the PUSCH radio resource, and transfer it to the upperstation. The process then terminates.

(Step S119) The control section 14 determines whether or not it detectsa random access preamble which the mobile station 20 transmits on PRACH.If the control section 14 detects a random access preamble which themobile station 20 transmits on PRACH, then step S120 is performed. Ifthe control section 14 does not detect a random access preamble whichthe mobile station 20 transmits on PRACH, then step S115 is performed.

(Step S120) The radio communication section 11 performs a random accessprocedure with the mobile station 20. After that, the radiocommunication section 11 and the wired communication section 13 extractdata which the mobile station 20 transmits, and transfer it to the upperstation.

FIG. 9 is a flow chart of a process performed by the mobile station inthe second embodiment. The process indicated in FIG. 9 will be describedin order of step number.

(Step S121) On the basis of notification from the base station 10, thecontrol section 23 configures an available UL radio resource. Morespecifically, if the base station 10 notifies the mobile station 20 of aCB-RNTI, then the control section 23 configures a CB resource indicatedby a CB grant which the mobile station 20 receives later as an availableUL radio resource. If the base station 10 notifies the mobile station 20of a PUCCH radio resource, then the control section 23 configures it asan available UL radio resource.

(Step S122) The control section 23 determines whether or not it detectsdata to be transmitted to the base station 10. If the control section 23detects data to be transmitted to the base station 10, then the controlsection 23 proceeds to step S123. If the control section 23 does notdetect data to be transmitted to the base station 10, then the controlsection 23 repeats step S122. That is to say, the control section 23waits until it detects data to be transmitted to the base station 10.

(Step S123) The control section 23 selects a first method from among therandom access method, the scheduling request method, and the contentionbased uplink access method according to a state in which an available ULradio resource is configured. More specifically, if a CB resource can beused, then the control section 23 selects the random access method orthe contention based uplink access method. If a PUCCH radio resource canbe used, then the control section 23 selects the random access method orthe scheduling request method (preferably the scheduling requestmethod). The transmission processing section 22 performs a procedure forthe selected method.

(Step S124) The control section 23 determines whether or not theprocedure performed in step S123 succeeds. If the procedure performed instep S123 succeeds, then the control section 23 terminates the process.If the procedure performed in step S123 fails, then the control section23 proceeds to step S125.

(Step S125) The control section 23 determines whether or not time whichelapses after the first beginning of the procedure in step S123 isshorter than determined time (or whether or not the number of times theprocedure is performed in step S123 is smaller than a determined numberof times). If time which elapses after the first beginning of theprocedure in step S123 is shorter than the determined time (or if thenumber of times the procedure is performed in step S123 is smaller thanthe determined number of times), then the control section 23 proceeds tostep S123. The transmission processing section 22 performs again theprocedure for the selected first method. If time which elapses after thefirst beginning of the procedure in step S123 is not shorter than thedetermined time (or if the number of times the procedure is performed instep S123 is not smaller than the determined number of times), then thecontrol section 23 proceeds to step S126.

(Step S126) The control section 23 selects a second method which is notselected in step S123 from among the random access method, thescheduling request method, and the contention based uplink access methodaccording to a state in which an available UL radio resource isconfigured. More specifically, if a CB resource can be used, then thecontrol section 23 selects one of the random access method and thecontention based uplink access method which is not yet selected. If aPUCCH radio resource can be used, then the control section 23 selectsone of the random access method and the scheduling request method whichis not yet selected. The transmission processing section 22 performs aprocedure for the selected method.

(Step S127) The control section 23 determines whether or not theprocedure performed in step S126 succeeds. If the procedure performed instep S126 succeeds, then the control section 23 terminates the process.If the procedure performed in step S126 fails, then the control section23 proceeds to step S128.

(Step S128) The control section 23 determines whether or not time whichelapses after the first beginning of the procedure in step S126 isshorter than determined time (or whether or not the number of times theprocedure is performed in step S126 is smaller than a determined numberof times). If time which elapses after the first beginning of theprocedure in step S126 is shorter than the determined time (or if thenumber of times the procedure is performed in step S126 is smaller thanthe determined number of times), then the control section 23 proceeds tostep S126. The transmission processing section 22 performs again theprocedure for the selected second method. If time which elapses afterthe first beginning of the procedure in step S126 is not shorter thanthe determined time (or if the number of times the procedure isperformed in step S126 is not smaller than the determined number oftimes), then step S129 is performed.

(Step S129) The transmission processing section 22 performs a procedureto be performed at the time of failure in data transmission. Forexample, the transmission processing section 22 performs a procedure foran RLF (Radio Link Failure) which is a process in an upper layer. Theprocedure for the RLF is described in, for example, “Evolved UniversalTerrestrial Radio Access (E-UTRA) Radio Resource Control (RRC) Protocolspecification” (3GPP TS 36.331 V9.1.0, 2009-12).

FIG. 10 is a first example of a sequence in the second embodiment.

(Step S131) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S132) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S133) The mobile station 20 uses a CB resource indicated by the CBgrant which the mobile station 20 receives in step S132 for transmittingdata to the base station 10. It is assumed that data transmission failsbecause of the occurrence of contention.

(Step S134) The mobile station 20 uses a CB resource indicated by thelatest CB grant which the mobile station 20 receives for retransmittingthe data to the base station 10. It is assumed that data transmissionfails because of the occurrence of contention.

(Step S135) The mobile station 20 detects that time-out occurs (or acounter reaches its upper limit) in the contention based uplink accessmethod. Then the mobile station 20 terminates a procedure for thecontention based uplink access method and performs switching to therandom access method. A time-out period (or the upper limit of thecounter) is designated in advance by, for example, the base station 10.

(Step S136) The mobile station 20 transmits a random access preambleusing a signature selected at random to the base station 10 over PRACH.

(Step S137) The base station 10 returns a random access response.

(Step S138) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S139) The base station 10 transmits a contention resolution to themobile station 20. After that, the mobile station 20 transmits the datato the base station 10.

In the example of a sequence indicated in FIG. 10, as has beendescribed, permission to use the CB resource is granted. In this case,the mobile station 20 preferentially selects the contention based uplinkaccess method and then selects the random access method. If datatransmission performed using the CB resource succeeds, this way enhancescommunication efficiency.

FIG. 11 is a second example of a sequence in the second embodiment.

(Step S141) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S142) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S143) The mobile station 20 uses a CB resource for transmittingdata to the base station 10. It is assumed that data transmission failsbecause of the occurrence of contention.

(Step S144) Even before time-out occurs (or the counter reaches itsupper limit), the mobile station 20 autonomously terminates a procedurefor the contention based uplink access method and performs switching tothe random access method. If the mobile station 20 performs switching tothe random access method, then the mobile station 20 does not performagain the procedure for the contention based uplink access method. Inthe example of FIG. 11, after transmission fails once, the mobilestation 20 performs switching to the random access method. However,after transmission fails a determined number of times (two times, forexample) which is smaller than the upper limit of the counter, themobile station 20 may perform switching to the random access method.

(Step S145) The mobile station 20 transmits a random access preamble tothe base station 10.

(Step S146) The base station 10 returns a random access response.

(Step S147) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S148) The base station 10 transmits a contention resolution to themobile station 20. After that, the mobile station 20 transmits data tothe base station 10.

In the example of a sequence indicated in FIG. 11, as has beendescribed, the timing at which switching from the contention baseduplink access method to the random access method is performed is earlierthan the timing at which switching from the contention based uplinkaccess method to the random access method is performed in FIG. 10. Evenin a state in which many mobile stations perform UL data transmissionand in which the probability of contention is high, this way makes itpossible to rapidly cancel an error.

FIG. 12 is a third example of a sequence in the second embodiment.

(Step S151) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S152) The mobile station 20 transmits a random access preamble tothe base station 10. It is assumed that random access contention occurs.

(Step S153) The base station 10 returns a random access response.

(Step S154) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S155) The base station 10 cannot detect a C-RNTI of the mobilestation 20 because of the occurrence of the contention and fails intransmitting a contention resolution.

(Step S156) The mobile station 20 performs again random access, butrandom access contention occurs. Accordingly, the base station 10 failsin transmitting a contention resolution.

(Step S157) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the random access method. Then themobile station 20 terminates the procedure for the random access methodand performs switching to the contention based uplink access method. Atime-out period (or the upper limit of the counter) is designated inadvance by, for example, the base station 10.

(Step S158) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S159) The mobile station 20 uses a CB resource indicated by the CBgrant which the mobile station 20 receives in step S158 for transmittingdata to the base station 10.

In the example of a sequence indicated in FIG. 12, as has beendescribed, permission to use the CB resource is granted. In this case,the mobile station 20 preferentially selects the random access methodand then selects the contention based uplink access method. Even if theprocedure for the random access method fails, this way makes it possibleto rapidly cancel an error without performing a process (RLF process,for example) in an upper layer.

FIG. 13 is a fourth example of a sequence in the second embodiment.

(Step S161) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S162) The mobile station 20 transmits a random access preamble tothe base station 10. It is assumed that random access contention occurs.

(Step S163) The base station 10 returns a random access response.

(Step S164) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S165) Because of the occurrence of the contention, the basestation 10 fails in transmitting a contention resolution.

(Step S166) Even before time-out occurs (or the counter reaches itsupper limit), the mobile station 20 autonomously terminates a procedurefor the random access method and performs switching to the contentionbased uplink access method. If the mobile station 20 performs switchingto the contention based uplink access method, then the mobile stationdoes not perform again the procedure for the random access method. Inthe example of FIG. 13, after transmission fails once, the mobilestation 20 performs switching to the contention based uplink accessmethod. However, after transmission fails a determined number of times(two times, for example) which is smaller than the upper limit of thecounter, the mobile station 20 may perform switching to the contentionbased uplink access method.

(Step S167) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S168) The mobile station 20 uses a CB resource for transmittingdata to the base station 10.

In the example of a sequence indicated in FIG. 13, as has beendescribed, the timing at which switching from the random access methodto the contention based uplink access method is performed is earlierthan the timing at which switching from the random access method to thecontention based uplink access method is performed in FIG. 12. Even in astate in which many mobile stations perform random access and in whichthe probability of contention is high, this way makes it possible torapidly cancel an error.

In the above mobile communication system according to the secondembodiment the base station 10 can execute control so as to prevent themobile station 20 or 20 a from applying both of the contention baseduplink access method and the scheduling request method. In addition, themobile station 20 or 20 a can execute control so as not to apply therandom access method and the contention based uplink access method orthe random access method and the scheduling request method in parallel.As a result, efficiency in UL data transmission from the mobile station20 or 20 a to the base station 10 is improved.

Third Embodiment

A third embodiment will now be described. The differences between theabove second embodiment and a third embodiment will mainly be describedand descriptions of the same matters will be omitted. In a mobilecommunication system according to a third embodiment a mobile stationselects the contention based uplink access method or the schedulingrequest method.

A mobile communication system according to a third embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in a third embodiment canbe realized by adopting the same structures that the base station andthe mobile station 20 in the second embodiment illustrated in FIGS. 6and 7, respectively, have. A third embodiment will now be described bythe use of the same reference numerals that are used in FIGS. 2, 6, and7.

FIG. 14 is a flow chart of a process performed by a base station in thethird embodiment. The process indicated in FIG. 14 will be described inorder of step number.

(Step S211) A radio communication section 11 notifies a mobile station20 of a CB-RNTI. In addition, the radio communication section 11continuously notifies the mobile station 20 of a CB grant indicating aCB resource.

(Step S212) A scheduler 112 assigns a PUCCH radio resource to the mobilestation 20. The radio communication section 11 notifies the mobilestation 20 of the radio resource assigned thereto.

(Step S213) A control section 14 determines whether or not it detectsdata which the mobile station 20 transmits using the CB resource. If thecontrol section 14 detects data which the mobile station 20 transmitsusing the CB resource, then step S214 is performed. If the controlsection 14 does not detect data which the mobile station 20 transmitsusing the CB resource, then step S215 is performed.

(Step S214) The radio communication section 11 and a wired communicationsection 13 extract the data detected in step S213, and transfer it to anupper station. The process then terminates.

(Step S215) The control section 14 determines whether or not it detectsa scheduling request which the mobile station 20 transmits using thePUCCH radio resource assigned thereto in step S212. If the controlsection 14 detects a scheduling request which the mobile station 20transmits using the PUCCH radio resource assigned thereto in step S212,then step S216 is performed. If the control section 14 does not detect ascheduling request which the mobile station 20 transmits using the PUCCHradio resource assigned thereto in step S212, then step S217 isperformed.

(Step S216) The scheduler 12 assigns a PUSCH radio resource to themobile station 20. After that, the radio communication section 11 andthe wired communication section 13 extract data which the mobile station20 transmits using the PUSCH radio resource, and transfer it to theupper station. The process then terminates.

(Step S217) The control section 14 determines whether or not it detectsa random access preamble which the mobile station 20 transmits on PRACH.If the control section 14 detects a random access preamble which themobile station 20 transmits on PRACH, then step S218 is performed. Ifthe control section 14 does not detect a random access preamble whichthe mobile station 20 transmits on PRACH, then step S213 is performed.

(Step S218) The radio communication section 11 performs a random accessprocedure with the mobile station 20. After that, the radiocommunication section 11 and the wired communication section 13 extractdata which the mobile station 20 transmits, and transfer it to the upperstation.

FIG. 15 is a flow chart of a process performed by the mobile station inthe third embodiment. The process indicated in FIG. 15 will be describedin order of step number.

(Step S221) On the basis of notification from the base station 10, acontrol section 23 configures an available UL radio resource. Morespecifically, the control section 23 configures both of a CB resourceindicated by a CB grant and a PUCCH radio resource as an available ULradio resource.

(Step S222) The control section 23 determines whether or not it detectsdata to be transmitted to the base station 10. If the control section 23detects data to be transmitted to the base station 10, then the controlsection 23 proceeds to step S223. If the control section 23 does notdetect data to be transmitted to the base station 10, then the controlsection 23 repeats step S222. That is to say, the control section 23waits until it detects data to be transmitted to the base station 10.

(Step S223) The control section 23 determines whether or not a CBresource and a PUCCH radio resource which can be used next belong to thesame subframe. If a CB resource and a PUCCH radio resource which can beused next belong to the same subframe, then the control section 23proceeds to step S224. If a CB resource and a PUCCH radio resource whichcan be used next belong to different subframes, then the control section23 proceeds to step S225.

(Step S224) The control section 23 selects a determined method from thecontention based uplink access method and the scheduling request method.After that, the control section 23 proceeds to step S226.

(Step S225) The control section 23 selects one of the contention baseduplink access method and the scheduling request method according to thetiming of the CB resource and the PUCCH radio resource. For example, thecontrol section 23 selects a method using a radio resource the timing ofwhich is earlier.

(Step S226) The control section 23 determines whether or not it selectsthe contention based uplink access method. If the control section 23selects the contention based uplink access method, then step S227 isperformed. If the control section 23 does not select the contentionbased uplink access method, then step S228 is performed.

(Step S227) A transmission processing section 22 performs a procedurefor the contention based uplink access method. That is to say, thetransmission processing section 22 transmits data to the base station 10using the CB resource.

(Step S228) The transmission processing section 22 performs a procedurefor the scheduling request method. That is to say, the transmissionprocessing section 22 transmits a scheduling request to the base station10 using the PUCCH radio resource and transmits data to the base station10 using an assigned PUSCH radio resource.

FIG. 16 is a first example of a sequence in the third embodiment.

(Step S231) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S232) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S233) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S234) The mobile station 20 selects the scheduling request method.

(Step S235) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource of which the base station10 notifies the mobile station 20 in step S232.

(Step S236) The base station 10 assigns a PUSCH radio resource to themobile station 20 and notifies the mobile station 20 of a UL grant.

(Step S237) The mobile station 20 transmits data to the base station 10using a radio resource indicated by the UL grant of which the basestation 10 notifies the mobile station 20.

In the example of a sequence indicated in FIG. 16, as has beendescribed, permission to use a CB resource is granted and the PUCCHradio resource is assigned. In this case, the mobile station 20preferentially selects the scheduling request method. This way makes itpossible to increase the probability by avoiding the occurrence ofcontention that a data transmission procedure will succeed at the firstattempt.

FIG. 17 is a second example of a sequence in the third embodiment.

(Step S241) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S242) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S243) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S244) The mobile station 20 selects the contention based uplinkaccess method.

(Step S245) The mobile station 20 transmits data to the base station 10using a CB resource indicated by the CB grant which the mobile station20 receives in step S243.

In the example of a sequence indicated in FIG. 17, as has beendescribed, permission to use the CB resource is granted and the PUCCHradio resource is assigned. In this case, the mobile station 20preferentially selects the contention based uplink access method. Ifcontention does not occur, this way reduces overhead before thebeginning of transmission and enhances communication efficiency. Fromthe viewpoint of communication efficiency, it is desirable to select thecontention based uplink access method.

In the above mobile communication system according to the thirdembodiment the mobile station 20 or 20 a can execute control so as notto apply the contention based uplink access method and the schedulingrequest method in parallel. In addition, the mobile station 20 or 20 acan select one of the contention based uplink access method and thescheduling request method to be applied. As a result, efficiency in ULdata transmission from the mobile station 20 or 20 a to the base station10 is improved.

In the above third embodiment a selection from the scheduling requestmethod and the contention based uplink access method is described.However, a selection from the random access method and the contentionbased uplink access method can also be controlled in the same way. Thatis to say, even if both of a PRACH radio resource and a CB resource areincluded in the same subframe, one of the random access method and thecontention based uplink access method can be selected by executing thesame control that is described above.

Fourth Embodiment

A fourth embodiment will now be described. The differences between theabove second and third embodiments and a fourth embodiment will mainlybe described and descriptions of the same matters will be omitted. In amobile communication system according to a fourth embodiment a mobilestation selects one of the contention based uplink access method and thescheduling request method according to the type of data to betransmitted.

A mobile communication system according to a fourth embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in a fourth embodiment canbe realized by adopting the same structures that the base station andthe mobile station 20 in the second embodiment illustrated in FIGS. 6and 7, respectively, have. A fourth embodiment will now be described bythe use of the same reference numerals that are used in FIGS. 2, 6, and7.

FIG. 18 is a flow chart of a process performed by a mobile station inthe fourth embodiment. The process indicated in FIG. 18 will bedescribed in order of step number. A process performed by a base stationin the fourth embodiment is the same as that indicated in FIG. 14 andperformed by the base station in the third embodiment.

(Step S311) On the basis of notification from the base station 10, acontrol section 23 configures both of a CB resource and a PUCCH radioresource as an available UL radio resource.

(Step S312) The control section 23 determines whether or not it detectsdata to be transmitted to the base station 10. If the control section 23detects data to be transmitted to the base station 10, then the controlsection 23 proceeds to step S313. If the control section 23 does notdetect data to be transmitted to the base station 10, then the controlsection 23 repeats step S312. That is to say, the control section 23waits until it detects data to be transmitted to the base station 10.

(Step S313) The control section 23 determines whether or not the datadetected in step S312 is an RRC message. If the data detected in stepS312 is an RRC message, then the control section 23 proceeds to stepS314. If the data detected in step S312 is not an RRC message, then thecontrol section 23 proceeds to step S315. An RRC message is an RRCconnection reconfiguration request, an RRC connection establishmentrequest, an RRC connection re-establishment request, or the like.

(Step S314) The control section 23 selects a determined method from thecontention based uplink access method and the scheduling request method.After that, the control section 23 proceeds to step S316.

(Step S315) The control section 23 selects one of the contention baseduplink access method and the scheduling request method on the basis ofthe timing of the CB resource and the PUCCH radio resource.

(Step S316) The control section 23 determines whether or not it selectsthe contention based uplink access method. If the control section 23selects the contention based uplink access method, then step S317 isperformed. If the control section 23 does not select the contentionbased uplink access method, then step S318 is performed.

(Step S317) A transmission processing section 22 performs a procedurefor the contention based uplink access method. That is to say, thetransmission processing section 22 transmits data to the base station 10using the CB resource.

(Step S318) The transmission processing section 22 performs a procedurefor the scheduling request method. That is to say, the transmissionprocessing section 22 transmits a scheduling request to the base station10 and then transmits data to the base station 10.

FIG. 19 is a first example of a sequence in the fourth embodiment.

(Step S321) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S322) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S323) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S324) The mobile station 20 detects an RRC message as data to betransmitted to the base station 10. The mobile station 20 then selectsthe scheduling request method.

(Step S325) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource of which the base station10 notifies the mobile station 20 in step S322.

(Step S326) The base station 10 assigns a PUSCH radio resource to themobile station 20 and notifies the mobile station 20 of a UL grant.

(Step S327) The mobile station 20 transmits the RRC message to the basestation 10 using a radio resource indicated by the UL grant of which thebase station 10 notifies the mobile station 20.

In the example of a sequence indicated in FIG. 19, as has beendescribed, the mobile station 20 preferentially selects the schedulingrequest method in the case of transmitting the RRC message.

FIG. 20 is a second example of a sequence in the fourth embodiment.

(Step S331) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S332) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S333) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S334) The mobile station 20 detects an RRC message as data to betransmitted to the base station 10. The mobile station 20 then selectsthe contention based uplink access method.

(Step S335) The mobile station 20 transmits the data to the base station10 using a CB resource indicated by the CB grant which the mobilestation 20 receives in step S333. In the example of a sequence indicatedin FIG. 20, as has been described, the mobile station 20 preferentiallyselects the contention based uplink access method in the case oftransmitting the RRC message. From the viewpoint of communicationefficiency, it is desirable to select the contention based uplink accessmethod.

An RRC message is data of high importance and a communication delay islikely to occur. Accordingly, in FIGS. 18 through 20, an RRC message isdistinguished from data of another type to select a UL data transmissionmethod. However, data of a determined type may be distinguished fromdata of another type in place of an RRC message to select a UL datatransmission method.

In the above mobile communication system according to the fourthembodiment the mobile station 20 or 20 a can execute control so as notto apply the contention based uplink access method and the schedulingrequest method in parallel. In addition, the mobile station 20 or 20 acan select according to the type of data to be transmitted one of thecontention based uplink access method and the scheduling request methodto be applied. As a result, efficiency in UL data transmission from themobile station 20 or 20 a to the base station 10 is improved.

In the above fourth embodiment a selection from the scheduling requestmethod and the contention based uplink access method is described.However, a selection from the random access method and the contentionbased uplink access method can also be controlled in the same way. Thatis to say, one of the random access method and the contention baseduplink access method can be selected according to the type of data to betransmitted by executing the same control that is described above.

Fifth Embodiment

A fifth embodiment will now be described. The differences between theabove second through fourth embodiments and a fifth embodiment willmainly be described and descriptions of the same matters will beomitted. In a mobile communication system according to a fifthembodiment the three methods, that is to say, the random access method,the scheduling request method, and the contention based uplink accessmethod are followed directly.

A mobile communication system according to a fifth embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in a fifth embodiment canbe realized by adopting the same structures that the base station andthe mobile station 20 in the second embodiment illustrated in FIGS. 6and 7, respectively, have. A fifth embodiment will now be described bythe use of the same reference numerals that are used in FIGS. 2, 6, and7.

FIG. 21 is a flow chart of a process performed by a mobile station inthe fifth embodiment. The process indicated in FIG. 21 will be describedin order of step number. A process performed by a base station in thefifth embodiment is the same as that indicated in FIG. 14 and performedby the base station in the third embodiment.

(Step S411) On the basis of notification from the base station 10, acontrol section 23 configures both of a CB resource and a PUCCH radioresource as an available UL radio resource.

(Step S412) The control section 23 determines whether or not it detectsdata to be transmitted to the base station 10. If the control section 23detects data to be transmitted to the base station 10, then the controlsection 23 proceeds to step S413. If the control section 23 does notdetect data to be transmitted to the base station 10, then the controlsection 23 repeats step S412. That is to say, the control section 23waits until it detects data to be transmitted to the base station 10.

(Step S413) The control section 23 selects a first method from therandom access method, the scheduling request method, and the contentionbased uplink access method. A transmission processing section 22performs a procedure for the selected method.

(Step S414) The control section 23 determines whether or not theprocedure performed in step S413 succeeds. If the procedure performed instep S413 succeeds, then the control section 23 terminates the process.If the procedure performed in step S413 fails, then the control section23 proceeds to step S415.

(Step S415) The control section 23 determines whether or not time whichelapses after the first beginning of the procedure in step S413 isshorter than determined time (or whether or not the number of times theprocedure is performed in step S413 is smaller than a determined numberof times). If time which elapses after the first beginning of theprocedure in step S413 is shorter than the determined time (or if thenumber of times the procedure is performed in step S413 is smaller thanthe determined number of times), then the control section 23 proceeds tostep S413. The transmission processing section 22 performs again theprocedure for the first method. If time which elapses after the firstbeginning of the procedure in step S413 is not shorter than thedetermined time (or if the number of times the procedure is performed instep S413 is not smaller than the determined number of times), then thecontrol section 23 terminates the procedure for the first method andproceeds to step S416.

(Step S416) The control section 23 selects a second method which is notyet selected in step S413. The transmission processing section 22performs a procedure for the selected method.

(Step S417) The control section 23 determines whether or not theprocedure performed in step S416 succeeds. If the procedure performed instep S416 succeeds, then the control section 23 terminates the process.If the procedure performed in step S416 fails, then the control section23 proceeds to step S418.

(Step S418) The control section 23 determines whether or not time whichelapses after the first beginning of the procedure in step S416 isshorter than determined time (or whether or not the number of times theprocedure is performed in step S416 is smaller than a determined numberof times). If time which elapses after the first beginning of theprocedure in step S416 is shorter than the determined time (or if thenumber of times the procedure is performed in step S416 is smaller thanthe determined number of times), then the control section 23 proceeds tostep S416. The transmission processing section 22 performs again theprocedure for the second method. If time which elapses after the firstbeginning of the procedure in step S416 is not shorter than thedetermined time (or if the number of times the procedure is performed instep S416 is not smaller than the determined number of times), then thecontrol section 23 terminates the procedure for the second method andproceeds to step S419.

(Step S419) The control section 23 selects a third method which is notyet selected. The transmission processing section 22 performs aprocedure for the selected method.

(Step S420) The control section 23 determines whether or not theprocedure performed in step S419 succeeds. If the procedure performed instep S419 succeeds, then the control section 23 terminates the process.If the procedure performed in step S419 fails, then the control section23 proceeds to step S421.

(Step S421) The control section 23 determines whether or not time whichelapses after the first beginning of the procedure in step S419 isshorter than determined time (or whether or not the number of times theprocedure is performed in step S419 is smaller than a determined numberof times). If time which elapses after the first beginning of theprocedure in step S419 is shorter than the determined time (or if thenumber of times the procedure is performed in step S419 is smaller thanthe determined number of times), then the control section 23 proceeds tostep S419. The transmission processing section 22 performs again theprocedure for the third method. If time which elapses after the firstbeginning of the procedure in step S419 is not shorter than thedetermined time (or if the number of times the procedure is performed instep S419 is not smaller than the determined number of times), then thecontrol section 23 terminates the procedure for the third method andstep S422 is performed.

(Step S422) The transmission processing section 22 performs a procedureto be performed at the time of failure in data transmission. Forexample, the transmission processing section 22 performs a procedure forthe RLF.

FIG. 22 is a first example of a sequence in the fifth embodiment.

(Step S431) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S432) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S433) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. It is assumed that themobile station 20 fails in transmitting the scheduling request.

(Step S434) The mobile station 20 retransmits a scheduling request tothe base station 10 using the next PUCCH radio resource. It is assumedthat the mobile station 20 fails in retransmitting the schedulingrequest.

(Step S435) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the scheduling request method. Thenthe mobile station 20 terminates a procedure for the scheduling requestmethod and performs switching to the contention based uplink accessmethod.

(Step S436) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S437) The mobile station 20 transmits data to the base station 10using a CB resource. It is assumed that the mobile station 20 fails intransmitting the data because of the occurrence of contention.

(Step S438) The mobile station 20 retransmits the data to the basestation 10 using the next CB resource. It is assumed that the mobilestation 20 fails in retransmitting the data because of the occurrence ofcontention.

(Step S439) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the contention based uplink accessmethod. Then the mobile station 20 terminates a procedure for thecontention based uplink access method and performs switching to therandom access method.

(Step S440) The mobile station 20 transmits a random access preamble tothe base station 10 on PRACH.

(Step S441) The base station 10 returns a random access response.

(Step S442) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S443) The base station 10 transmits a contention resolution to themobile station 20. After that, the mobile station 20 transmits the datato the base station 10.

FIG. 23 is a second example of a sequence in the fifth embodiment.

(Step S451) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S452) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S453) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S454) The mobile station 20 transmits data to the base station 10using a CB resource. It is assumed that the mobile station 20 fails intransmitting the data because of the occurrence of contention.

(Step S455) The mobile station 20 retransmits the data to the basestation 10 using the next CB resource. It is assumed that the mobilestation 20 fails in retransmitting the data because of the occurrence ofcontention.

(Step S456) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the contention based uplink accessmethod. Then the mobile station 20 terminates a procedure for thecontention based uplink access method and performs switching to thescheduling request method.

(Step S457) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. It is assumed that themobile station 20 fails in transmitting the scheduling request.

(Step S458) The mobile station 20 retransmits a scheduling request tothe base station 10 using the next PUCCH radio resource. It is assumedthat the mobile station 20 fails in retransmitting the schedulingrequest.

(Step S459) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the scheduling request method. Thenthe mobile station 20 terminates a procedure for the scheduling requestmethod and performs switching to the random access method.

(Step S460) The mobile station 20 transmits a random access preamble tothe base station 10 on PRACH.

(Step S461) The base station 10 returns a random access response.

(Step S462) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S463) The base station 10 transmits a contention resolution to themobile station 20. After that, the mobile station 20 transmits the datato the base station 10.

FIG. 24 is a third example of a sequence in the fifth embodiment.

(Step S471) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S472) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S473) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. It is assumed that themobile station 20 fails in transmitting the scheduling request.

(Step S474) The mobile station 20 retransmits a scheduling request tothe base station 10 using the next PUCCH radio resource. It is assumedthat the mobile station 20 fails in retransmitting the schedulingrequest.

(Step S475) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the scheduling request method. Thenthe mobile station 20 terminates a procedure for the scheduling requestmethod and performs switching to the random access method.

(Step S476) The mobile station 20 transmits a random access preamble tothe base station 10 on PRACH. It is assumed that random accesscontention occurs.

(Step S477) The base station 10 returns a random access response.

(Step S478) The mobile station 20 transmits a scheduled transmission tothe base station 10.

(Step S479) The base station 10 cannot detect a C-RNTI of the mobilestation 20 because of the occurrence of the contention and fails intransmitting a contention resolution.

(Step S480) The base station 10 performs again random access, but randomaccess contention occurs. Accordingly, the base station 10 fails intransmitting a contention resolution.

(Step S481) The mobile station 20 detects that time-out occurs (or thecounter reaches its upper limit) in the random access method. Then themobile station 20 terminates the procedure for the random access methodand performs switching to the contention based uplink access method.

(Step S482) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S483) The mobile station 20 uses a CB resource for transmittingdata to the base station 10.

In the above mobile communication system according to the fifthembodiment the mobile station 20 or 20 a can execute control so as notto apply the random access method, the scheduling request method, andthe contention based uplink access method in parallel. As a result,efficiency in UL data transmission from the mobile station 20 or 20 a tothe base station 10 is improved. In addition, procedures for a maximumof three methods are performed in series, so the probability of successin data transmission finally increases.

Sixth Embodiment

A sixth embodiment will now be described. The differences between theabove second through fifth embodiments and a sixth embodiment willmainly be described and descriptions of the same matters will beomitted. In a mobile communication system according to a sixthembodiment it is assumed that after a procedure for the schedulingrequest method is begun, a state in which the contention based uplinkaccess method can be applied arises. In this case, the procedure for thescheduling request method is canceled and switching to the contentionbased uplink access method is performed.

A mobile communication system according to a sixth embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in a sixth embodiment canbe realized by adopting the same structures that the base station 10 andthe mobile station 20 in the second embodiment illustrated in FIGS. 6and 7, respectively, have. A sixth embodiment will now be described bythe use of the same reference numerals that are used in FIGS. 2, 6, and7.

FIG. 25 is a flow chart of a process performed by a base station in thesixth embodiment. The process indicated in FIG. 25 will be described inorder of step number.

(Step S511) A radio communication section 11 notifies a mobile station20 of a CB-RNTI.

(Step S512) A scheduler 112 assigns a PUCCH radio resource to the mobilestation 20. The radio communication section 11 notifies the mobilestation 20 of the radio resource assigned thereto.

(Step S513) The radio communication section 11 notifies the mobilestation 20 of a CB grant. Right (in a determined period of time, forexample) after that, the radio communication section 11 receives ascheduling request from the mobile station 20.

(Step S514) A control section 14 determines whether or not it ignoresthe scheduling request received in step S513 (whether or not setting isconfigured so as to ignore the scheduling request received in stepS513). If the control section 14 ignores the scheduling request receivedin step S513, then the control section 14 does not respond to thescheduling request and step S518 is performed. If the control section 14does not ignore the scheduling request received in step S513, then stepS515 is performed.

(Step S515) The scheduler 12 assigns a PUSCH radio resource to themobile station 20. The radio communication section 11 notifies themobile station 20 of the radio resource assigned thereto.

(Step S516) The control section 14 determines whether or not a BSR(Buffer Status Report) is received by the radio resource assigned instep S515. If a BSR is received by the radio resource assigned in stepS515, then step S517 is performed. If a BSR is not received by the radioresource assigned in step S515, then step S518 is performed.

(Step S517) The control section 14 normally terminates the procedure forthe scheduling request method.

(Step S518) The radio communication section 11 and a wired communicationsection 13 extract data which the mobile station 20 transmits using a CBresource, and transfer it to an upper station.

FIG. 26 is a flow chart of a process performed by the mobile station inthe sixth embodiment. The process indicated in FIG. 26 will be describedin order of step number.

(Step S521) On the basis of notification from the base station 10, acontrol section 23 configures a PUCCH radio resource as an available ULradio resource.

(Step S522) The control section 23 determines whether or not it detectsdata to be transmitted to the base station 10. If the control section 23detects data to be transmitted to the base station 10, then the controlsection 23 proceeds to step S523. If the control section 23 does notdetect data to be transmitted to the base station 10, then the controlsection 23 repeats step S522. That is to say, the control section 23waits until it detects data to be transmitted to the base station 10.

(Step S523) A transmission processing section 22 transmits a schedulingrequest using the PUCCH radio resource. Right (in a determined period oftime, for example) after the transmission of the scheduling request bythe transmission processing section 22, a radio communication section 21receives a CB grant from the base station 10.

(Step S524) The control section 23 determines whether or not it cancelsthe procedure for the scheduling request method (whether or not settingis configured so as to cancel the procedure for the scheduling requestmethod). If the control section 23 cancels the procedure for thescheduling request method, then step S528 is performed. If the controlsection 23 does not cancel the procedure for the scheduling requestmethod, then step S525 is performed.

(Step S525) The control section 23 determines whether or not a PUSCHradio resource is assigned by the base station 10 as a response to thescheduling request transmitted in step S523. If a PUSCH radio resourceis assigned by the base station 10, then step S526 is performed. If aPUSCH radio resource is not assigned by the base station 10, then stepS528 is performed.

(Step S526) The transmission processing section 22 transmits a BSR tothe base station 10 using the assigned PUSCH radio resource.

(Step S527) The control section 23 normally terminates the procedure forthe scheduling request method.

(Step S528) The transmission processing section 22 transmits data to thebase station 10 using a CB resource indicated by the CB grant of whichthe base station 10 notifies the radio communication section 21 in stepS523.

FIG. 27 is a first example of a sequence in the sixth embodiment.

(Step S531) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S532) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S533) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S534) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. At this point of timethe mobile station 20 has not received the CB grant yet.

(Step S535) The base station 10 ignores the scheduling request receivedfrom the mobile station 20. That is to say, the base station 10 does notassign a PUSCH radio resource.

(Step S536) The mobile station 20 cancels the scheduling request method.

(Step S537) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S533. In the example of a sequence indicated in FIG.27, as has been described, the base station 10 receives the schedulingrequest and transmits the CB grant in the same period of time. Inaddition, the mobile station 20 transmits the scheduling request andreceives the CB grant in the same period of time. In this case, the basestation 10 or the mobile station 20 determines to stop the procedure forthe scheduling request method. This way makes it unnecessary to transmitor receive a message for canceling the scheduling request method. As aresult, radio resource consumption can be controlled.

FIG. 28 is a second example of a sequence in the sixth embodiment.

(Step S541) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S542) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S543) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S544) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. At this point of timethe mobile station 20 has not received the CB grant yet.

(Step S545) The base station 10 assigns a PUSCH radio resource to themobile station 20 and notifies the mobile station 20 of a UL grant.

(Step S546) The mobile station 20 transmits a BSR using the PUSCH radioresource assigned thereto in step S545. The mobile station 20 thencancels the scheduling request method.

(Step S547) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S543.

In the example of a sequence indicated in FIG. 28, as has beendescribed, the base station 10 receives the scheduling request andtransmits the CB grant in the same period of time. In addition, themobile station 20 transmits the scheduling request and receives the CBgrant in the same period of time. In this case, the mobile station 20transmits the BSR to the base station 10. By doing so, the mobilestation 20 cancels the scheduling request method. The LTE specificationalso prescribes that a procedure for the scheduling request methodshould terminate by BSR transmission. Accordingly, there is no need tomake a special determination for canceling the scheduling requestmethod. This makes it easy to control the base station 10 and the mobilestation 20.

In the above mobile communication system according to the sixthembodiment it is possible to perform switching to the contention baseduplink access method even after the beginning of a procedure for thescheduling request method by the mobile station 20 or 20 a. Thisprevents procedures for the scheduling request method and the contentionbased uplink access method from being performed in parallel. As aresult, efficiency in UL data transmission from the mobile station 20 or20 a to the base station 10 is improved.

Seventh Embodiment

A seventh embodiment will now be described. The differences between theabove second through sixth embodiments and a seventh embodiment willmainly be described and descriptions of the same matters will beomitted. In a mobile communication system according to a seventhembodiment, a procedure for the scheduling request method is canceledand a procedure for the contention based uplink access method isperformed. This is the same with the sixth embodiment.

A mobile communication system according to a seventh embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in a seventh embodimentcan be realized by adopting the same structures that the base station 10and the mobile station 20 in the second embodiment illustrated in FIGS.6 and 7, respectively, have. A seventh embodiment will now be describedby the use of the same reference numerals that are used in FIGS. 2, 6,and 7.

FIG. 29 is a flow chart of a process performed by a mobile station inthe seventh embodiment. Of steps S611 through S618, only the step S613described below differs from the process indicated in FIG. 26 andperformed by the mobile station in the sixth embodiment. A processperformed by a base station in the seventh embodiment is the same asthat indicated in FIG. 25 and performed by the base station in the sixthembodiment.

(Step S613) A radio communication section 21 receives a CB grant from abase station 10. A transmission processing section 22 transmits ascheduling request using a PUCCH radio resource right (in a determinedperiod of time, for example) after the receiving of the CB grant. In thefollowing case, for example, this may occur. While a CB grant is beinghandled, a scheduling request is transmitted. There is no time toexecute control for stopping the transmission of the scheduling request.

FIG. 30 is a first example of a sequence in the seventh embodiment.

(Step S621) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S622) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S623) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S624) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. At this point of time itis assumed that the mobile station 20 has received the CB grant and thatthe mobile station 20 cannot stop the transmission of the schedulingrequest.

(Step S625) The base station 10 ignores the scheduling request receivedfrom the mobile station 20. That is to say, the base station 10 does notassign a PUSCH radio resource.

(Step S626) The mobile station 20 cancels the scheduling request method.

(Step S627) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S623.

FIG. 31 is a second example of a sequence in the seventh embodiment.

(Step S631) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S632) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S633) The base station 10 notifies the mobile station 20 of a CBgrant.

(Step S634) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource. At this point of time itis assumed that the mobile station 20 has received the CB grant and thatthe mobile station 20 cannot stop the transmission of the schedulingrequest.

(Step S635) The base station 10 assigns a PUSCH radio resource to themobile station 20 and notifies the mobile station 20 of a UL grant.

(Step S636) The mobile station 20 transmits a BSR using the PUSCH radioresource assigned thereto in step S635. The mobile station 20 thencancels the scheduling request method.

(Step S637) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S633.

In the above mobile communication system according to the seventhembodiment it is possible to perform switching to the contention baseduplink access method even after the beginning of a procedure for thescheduling request method by the mobile station 20 or 20 a. This is thesame with the sixth embodiment. This prevents procedures for thescheduling request method and the contention based uplink access methodfrom being performed in parallel. As a result, efficiency in UL datatransmission from the mobile station 20 or 20 a to the base station 10is improved.

Eighth Embodiment

An eighth embodiment will now be described. The differences between theabove second through seventh embodiments and an eighth embodiment willmainly be described and descriptions of the same matters will beomitted. In a mobile communication system according to an eighthembodiment, a procedure for the scheduling request method is canceledand a procedure for the contention based uplink access method isperformed. This is the same with the sixth and seventh embodiments.

A mobile communication system according to an eighth embodiment can berealized by adopting the same structure that the mobile communicationsystem according to the second embodiment illustrated in FIG. 2 has. Inaddition, a base station and a mobile station in an eighth embodimentcan be realized by adopting the same structures that the base stationand the mobile station 20 in the second embodiment illustrated in FIGS.6 and 7, respectively, have. An eighth embodiment will now be describedby the use of the same reference numerals that are used in FIGS. 2, 6,and 7.

FIG. 32 is a first example of a sequence in the eighth embodiment.

(Step S711) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S712) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S713) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource.

(Step S714) The base station 10 notifies the mobile station 20 of a CBgrant. It is assumed that the base station 10 notifies the mobilestation 20 of a CB grant right (in a determined period of time, forexample) after the receiving of the scheduling request. In the followingcase, for example, this may occur. While a scheduling request is beinghandled, a CB grant is outputted. There is no time to execute controlfor stopping the outputting of the CB grant.

(Step S715) The base station 10 ignores the scheduling request receivedfrom the mobile station 20. That is to say, the base station 10 does notassign a PUSCH radio resource.

(Step S716) The mobile station 20 cancels the scheduling request method.

(Step S717) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S714.

FIG. 33 is a second example of a sequence in the eighth embodiment.

(Step S721) The base station 10 notifies the mobile station 20 of aCB-RNTI.

(Step S722) The base station 10 assigns a PUCCH radio resource to themobile station 20 and notifies the mobile station 20 of the PUCCH radioresource assigned thereto.

(Step S723) The mobile station 20 transmits a scheduling request to thebase station 10 using the PUCCH radio resource.

(Step S724) The base station 10 notifies the mobile station 20 of a CBgrant. At this point of time it is assumed that the base station 10 hasreceived the scheduling request and that the base station 10 cannot stopthe notification of the CB grant.

(Step S725) The base station 10 assigns a PUSCH radio resource to themobile station 20 and notifies the mobile station 20 of a UL grant.

(Step S726) The mobile station 20 transmits a BSR using the PUSCH radioresource assigned thereto in step S725. The mobile station 20 thencancels the scheduling request method.

(Step S727) The mobile station 20 transmits data to the base station 10using a CB resource of which the base station 10 notifies the mobilestation 20 in step S724.

In the above mobile communication system according to the eighthembodiment it is possible to perform switching to the contention baseduplink access method even after the beginning of a procedure for thescheduling request method by the mobile station 20 or 20 a. This is thesame with the sixth and seventh embodiments. This prevents proceduresfor the scheduling request method and the contention based uplink accessmethod from being performed in parallel. As a result, efficiency in ULdata transmission from the mobile station 20 or 20 a to the base station10 is improved.

According to the above radio communication apparatus, radiocommunication system, and radio communication method, data transmissioncan be performed efficiently in the case of a contention based radioresource being set.

All examples and conditional language provided herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

1. A radio communication apparatus used as one of a plurality of secondradio communication apparatus in a radio communication system in which afirst radio communication apparatus receives data from the plurality ofsecond radio communication apparatus, the radio communication apparatuscomprising: a detection section which detects a first radio resourcethat is assigned by the first radio communication apparatus and that canbe used on a contention basis by the plurality of second radiocommunication apparatus for data transmission; and a transmissionprocessing section which selectively performs, at the time of the firstradio resource being detected, one of a first transmission method usingthe first radio resource for data transmission and a second transmissionmethod using a second radio resource assigned by the first radiocommunication apparatus by which random access is performed for datatransmission.
 2. The radio communication apparatus according to claim 1,wherein when the transmission processing section fails in a procedurefor one of transmission methods between the first transmission methodand the second transmission method, the transmission processing sectionaborts the procedure for the one transmission method and performsanother transmission method.
 3. The radio communication apparatusaccording to claim 1, wherein when the first radio resource and thesecond radio resource are included in a prescribed radio transmissionunit, the transmission processing section selects one of transmissionmethods between the first transmission method and the secondtransmission method.
 4. The radio communication apparatus according toclaim 1, wherein the transmission processing section selects one of thefirst transmission method and the second transmission method accordingto a type of data.
 5. A radio communication apparatus used as one of aplurality of second radio communication apparatus in a radiocommunication system in which a first radio communication apparatusreceives data from the plurality of second radio communicationapparatus, the radio communication apparatus comprising: a detectionsection which detects a first radio resource that is assigned by thefirst radio communication apparatus and that can be used on a contentionbasis by the plurality of second radio communication apparatus for datatransmission and a second radio resource for a control channel assignedby the first radio communication apparatus; and a transmissionprocessing section which selectively performs, at the time of the firstradio resource and the second radio resource being detected, one of afirst transmission method using the first radio resource for datatransmission and a second transmission method using a third radioresource that is assigned by the first radio communication apparatusthrough an assignment request using the second radio resource for datatransmission.
 6. The radio communication apparatus according to claim 5,wherein when the first radio resource and the second radio resource areincluded in a prescribed radio transmission unit, the transmissionprocessing section selects one of transmission methods between the firsttransmission method and the second transmission method.
 7. The radiocommunication apparatus according to claim 5, wherein the transmissionprocessing section selects one of the first transmission method and thesecond transmission method according to a type of data.
 8. The radiocommunication apparatus according to claim 5, wherein when thetransmission processing section fails in a procedure for one oftransmission methods between the first transmission method and thesecond transmission method, the transmission processing section abortsthe procedure for the one transmission method and performs anothertransmission method.
 9. The radio communication apparatus according toclaim 8, wherein when the transmission processing section also fails ina procedure for said another transmission method, the transmissionprocessing section aborts the procedure for said another transmissionmethod and performs a third transmission method using a fourth radioresource that is assigned through random access by the first radiocommunication apparatus for data transmission.
 10. The radiocommunication apparatus according to claim 5, wherein when thetransmission processing section fails in a procedure for one oftransmission methods between the first transmission method and thesecond transmission method, the transmission processing section abortsthe procedure for the one transmission method and performs a thirdtransmission method using a fourth radio resource that is assignedthrough random access by the first radio communication apparatus fordata transmission.
 11. The radio communication apparatus according toclaim 5, wherein when the first radio resource is detected aftertransmitting the assignment request using the second radio resource, thetransmission processing section aborts a procedure for the secondtransmission method and performs the first transmission method.
 12. Theradio communication apparatus according to claim 11, wherein when thethird radio resource is assigned in response to the assignment requesttransmitted, the transmission processing section aborts the procedurefor the second transmission method by transmitting informationindicating a buffer state using the third radio resource.
 13. A radiocommunication apparatus used as a first radio communication apparatus ina radio communication system in which the first radio communicationapparatus receives data from a plurality of second radio communicationapparatus, the radio communication apparatus comprising: a controlsection which configures a first radio resource that can be used on acontention basis by the plurality of second radio communicationapparatus for data transmission, and which selects making each secondradio communication apparatus use the first radio resource or assigningto said each second radio communication apparatus a second radioresource used for transmitting a radio resource assignment request; anda notification section which selectively notifies said each second radiocommunication apparatus of information indicating permission to use thefirst radio resource or information indicating the assigned second radioresource according to a result of the selection by the control section.14. A radio communication apparatus used as one of a plurality of secondradio communication apparatus in a radio communication system in which afirst radio communication apparatus receives data from the plurality ofsecond radio communication apparatus, the radio communication apparatuscomprising: a detection section which detects at least one of a firstradio resource that is assigned by the first radio communicationapparatus and that can be used on a contention basis by the plurality ofsecond radio communication apparatus for data transmission and a secondradio resource for a control channel assigned by the first radiocommunication apparatus; and a transmission processing section whichselectively performs, according to a result of the detection by thedetection section, one of three or more transmission methods including afirst transmission method using the first radio resource for datatransmission, a second transmission method by which data transmission isperformed by performing a process using the second radio resource, and athird transmission method by which data transmission is performed byperforming a process different from the first transmission method or thesecond transmission method.
 15. The radio communication apparatusaccording to claim 14, wherein: in the second transmission method, thesecond radio resource is used for assignment request transmission and athird radio resource assigned by the first radio communication apparatusis used for data transmission; and in the third transmission method,random access is performed and a fourth radio resource assigned by thefirst radio communication apparatus is used for data transmission. 16.The radio communication apparatus according to claim 14, wherein thetransmission processing section selects and performs the three or moretransmission methods in order according to the result of the detectionby the detection section.
 17. A radio communication system in which afirst radio communication apparatus receives data from a plurality ofsecond radio communication apparatus, wherein: the first radiocommunication apparatus configures a first radio resource which can beused on a contention basis by the plurality of second radiocommunication apparatus for data transmission; the plurality of secondradio communication apparatus performs a first transmission method usingthe first radio resource for data transmission and a second transmissionmethod using a third radio resource that is assigned by the first radiocommunication apparatus through an assignment request using a secondradio resource for a control channel assigned by the first radiocommunication apparatus for data transmission; and each of the pluralityof second radio communication apparatus selectively performs one of thefirst transmission method and the second transmission method.
 18. Aradio communication method in a radio communication system in which afirst radio communication apparatus receives data from a plurality ofsecond radio communication apparatus, the method comprising:configuring, by the first radio communication apparatus, a first radioresource which can be used on a contention basis by the plurality ofsecond radio communication apparatus for data transmission; selectivelyperforming, by each of at least a part of the plurality of second radiocommunication apparatus, one of a first transmission method using thefirst radio resource for data transmission and a second transmissionmethod using a second radio resource for a control channel assigned bythe first radio communication apparatus for assignment requesttransmission; and assigning, by the first radio communication apparatus,a third radio resource for data transmission to a second radiocommunication apparatus which transmits an assignment request at thetime of the second transmission method being performed.